This invention relates to an electromagnetic control device for opening and closing contacts, comprised of a movable armature rotating between two stops. Said device is particularly suited for use in a low voltage power switch such as a contactor or contactor/breaker.
An electromagnetic control device comprising a mobile armature rotating between two positions formed by two stops arranged in a fixed frame and comprising at least one permanent magnet and at least one coil on a fixed frame (see patent application No FR9906592). The permanent magnet serves to maintain the mobile armature in a given position when the coil is not creating a magnetic field. Said device is bistable and, in order to switch the mobile armature from one position to another, it is necessary to circulate a current in the coil either in one direction or in the other or, if using two opposed coils, in such a fashion as to create a magnetic field, in one direction or in another, greater than that generated by the permanent magnet. Consumption by such a device is thus significant. In other respects, DE3005921 discloses a monostable electromagnetic control device, in which at least one magnet is counted on a mobile armature and a coil is mounted on the fixed frame. But the fact of mounting the coil or coils in the fixed frame involves an undesirable increase of the size of the entire device.
On the other hand, U.S. Pat. No. 5,029,618, discloses an electromagnetic control applied to a mechanism for textile machinery. Said device is either rotary and bistable or linear and monostable in virtue of an asymmetry of the air gap of the two magnets comprising it. Therefore, the power of the one device is not adapted for efficiently opening and closing the power contacts of a switching apparatus such as is desired in the invention.
The object of the present invention is to provide the simplest possible electromagnetic control device for a switching apparatus capable of responding to extreme constraints of space requirements and consumption.
In order to achieve this, the invention describes an electromagnetic control device for opening and closing contacts of a switching apparatus comprising:
a monostable mobile armature that is mobile in rotating about an axis of rotation within a fixed frame between two stops delimiting a inactive position and an active position, respectively, and which mechanically cooperates with an actuation lever for the contacts, the mobile armature comprising an elongated core along a longitudinal axis running perpendicular to the axis of rotation and having two convex opposing ends.
at least one permanent magnet mounted in the fixed frame along an axis of magnetization passing through the axis of rotation and having a polar surface that is substantially concave in shape with respect to at least one end of the mobile armature;
at least one coil mounted on the mobile armature;
control means capable of delivering a control current into said coil(s).
In the presence of a control current in the coil of a value of zero or less than the threshold of activation, the mobile armature switches to a first of the aforesaid two positions (inactive and active, respectively) by virtue of the force of attraction of the permanent magnet (s). In the presence of a command current of a value greater than the threshold of activation greater than or equal to the threshold of activation, the mobile armature switches to the second of the aforesaid two positions (inactive and active, respectively) by virtue of the force of repulsion of the permanent magnet(s).
According to one characteristic, the fixed frame comprises two permanent magnets that are positioned symmetrically relative to the axis of rotation of the mobile armature and which each have a polar surface that is substantially concave cooperating with one opposed convex end of the mobile armature in such a fashion as to minimize the forces necessary to the switching movements of the mobile armature. The longitudinal axis of the core of the mobile armature is always displaced on the same side relative to the axis of magnetization of the two permanent magnets.
The coil(s) is (are) mounted on the mobile armature by means of a cage or housing that encloses the core and which exhibits transverse clamps or rings at least one of which cooperating with an interior surface of the fixed frame.
According to another characteristic, the control means comprises an electronic circuit capable of receiving an input of an opening instruction and a closing instruction and delivering to the output a control current into the coil(s) (24, 25).
A further object of the invention is a switching apparatus equipped with one such electromagnetic control device.